I have been given a dozen of dump files. Using windbg/sosex command !dumpstack -EE, a lot of them show these lines by the end :
0aa6ce7c 028ea126 (MethodDesc 02756288 +0x16 TheCompany.Toolbox.Log.Logger.Info(System.String))
0aa6cecc 028ea126 (MethodDesc 02756288 +0x16 TheCompany.Toolbox.Log.Logger.Info(System.String))
0aa6cf54 028ea126 (MethodDesc 02756288 +0x16 TheCompany.Toolbox.Log.Logger.Info(System.String))
0aa6d080 6f42bc51 (MethodDesc 6f1da670 +0x81 System.TimeSpan.TimeToTicks(Int32, Int32, Int32))
0aa6d0a8 6f42c0a0 (MethodDesc 6f1daf1c +0x40 System.DateTime.TimeToTicks(Int32, Int32, Int32))
0aa6d0d0 6f42cb8f (MethodDesc 6f1da8ec +0x7f System.DateTime.Add(Double, Int32))
Unfortunately, trying to get the local variable with !clrstack -a does not give me sensible results:
0:045> !clrstack -a
OS Thread Id: 0xf50 (45)
Child SP IP Call Site
0aa6ed78 76df7094 [GCFrame: 0aa6ed78]
0aa6ef5c 76df7094 [DebuggerU2MCatchHandlerFrame: 0aa6ef5c]
Is there a way to move to another frame than the last one ? ( so as to get the locals in this frame).
In native mode, I can do :
.frame #$.frame +1
then I can have the locals in that previous frame with
dv
I wonder how to do the same with the managed stack, so as I can do !clrstack -a inside previous frames. I also would like to know the function parameters value/reference in this stackframe.
Are there commands to perform such actions ?
Steve Johnson's SOSEX has the !mframe command.
Although you have tagged the question sosex, you have not used any SOSEX command, only SOS commands, which could be a reason why you did not find the command.
You get the frame numbers from !mk. If you have DML enabled, the frame numbers can be clicked and a !mframe command is automatically done. After that, you can do !mdv to display arguments and locals.
Alternatively, !mdv <frame> also takes a frame number directly.
However, I'm not sure if this always helps. SOSEX can't do magic and needs to rely on the information given by the .NET framework. If that's broken for some reason, you could be unlucky.
Related
Using WinDbg with TTD enabled, how to play back to the moment of creation of some managed object?
Lets say I do have its address obtained using !clrstack -a or !dso
There are several ways of doing this. If you have the address of the object and want to go back to its creation you can use a ba (break on access). When an object is created the Method Table address is written into the first word (4 bytes for 32-bit, 8 bytes for 64-bit). So adding a breakpoint per write access and going backwards will stop at the object creation. Another way is to add breakpoints pointing to all constructors of the object and also going backwards. Also notice that all of this can also be done by a 'dx' command filtering by breakpoint address or constructor call.
Imagine you have this output:
0:016> !dso
OS Thread Id: 0x2f54 (16)
RSP/REG Object Name
000000A2CD5FC770 000001e9849cd4b8 ConceptNetConsole1.SampleClass1
(...)
0:016> !DumpObj /d 000001e9849cd4b8
Name: ConceptNetConsole1.SampleClass1
MethodTable: 00007ffb85545ef8 <<< This is the method table
EEClass: 00007ffb85542d68
Size: 136(0x88) bytes
File: C:\Projects\ConceptNetConsole1\ConceptNetConsole1\bin\x64\Release\ConceptNetConsole1.exe
Fields:
MT Field Offset Type VT Attr Value Name
00007ffbe38e70b0 40005a8 8 System.Object 0 instance 000001e9849cd718 __identity
(...)
Approach 1:
And you want to stop when this object is created you can use (for 32-bit use w4):
ba w8 000001e9849cd4b8
g-
Using 'dx' (notice that the address must be in C++ format, starting wit '0x'):
dx -g #$cursession.TTD.Memory(0x00001e9849cd4b8,0x00001e9849cd4b8+8,"w")
Again, for 32-bit use address+4 on the second parameter. The option -g will show in a grid format.
Approach 2:
Get the address(es) of the constructors by listing the methods table of the class:
0:016> !dumpmt -md 00007ffb85545ef8
EEClass: 00007ffb85542d68
Module: 00007ffb85545408
Name: ConceptNetConsole1.SampleClass1
mdToken: 0000000002000005
File: C:\Projects\ConceptNetConsole1\ConceptNetConsole1\bin\x64\Release\ConceptNetConsole1.exe
BaseSize: 0x88
ComponentSize: 0x0
Slots in VTable: 23
Number of IFaces in IFaceMap: 0
--------------------------------------
MethodDesc Table
Entry MethodDesc JIT Name
00007ffbe36fb1f0 00007ffbe3257538 PreJIT System.Object.ToString()
00007ffbe36ffd90 00007ffbe3257540 PreJIT System.Object.Equals(System.Object)
00007ffbe3721dc0 00007ffbe3257568 PreJIT System.Object.GetHashCode()
00007ffbe36fce50 00007ffbe3257580 PreJIT System.Object.Finalize()
00007ffbe37d8f40 00007ffbe333cfd0 PreJIT System.MarshalByRefObject.GetLifetimeService()
00007ffbe36f8b10 00007ffbe333cfd8 PreJIT System.MarshalByRefObject.InitializeLifetimeService()
00007ffbe37cbd80 00007ffbe333cfe0 PreJIT System.MarshalByRefObject.CreateObjRef(System.Type)
00007ffb85560090 00007ffb85545d58 JIT ConceptNetConsole1.SampleClass1..ctor() <<< This is the constructor
(...)
You may simply set the breakpoint at the 'Entry' address (or use !sos.bpmd) and go backwards:
bp 00007ffb85560090
g-
Or use 'dx' to show all occasions where the code was called (note that the code was again adjusted to look like C++ '0x' and also that is in quotes):
dx -g #$cursession.TTD.Calls("0x00007ffb85560090")
Hope it works for you.
I'm trying my driver with Driver Verifier turned on in Windows 7 x64, and get IRQL_NOT_LESS_OR_EQUAL(0A) bugcheck. From analyze -v info, it seems that the memory page of RtlAnsiCharToUnicodeChar function gets paged out, so calling that function causes bugcheck 0A . RtlAnsiCharToUnicodeChar is an ntoskrnl.exe exported function. Can it really be paged out? If so, how can I prevent it?
On spot debug info screen shot below:
yes. of course - very many ntoskrnl routines in PAGE* section.
RtlAnsiCharToUnicodeChar also paged - read in documentation:
IRQL <= APC_LEVEL
also read about DbgPrintEx routine
DbgPrint and DbgPrintEx can be called at IRQL<=DIRQL. However, Unicode
format codes (%wc and %ws) can be used only at IRQL = PASSIVE_LEVEL.
and
However, the Unicode format codes (%C, %S, %lc, %ls, %wc, %ws, and
%wZ) can only be used with IRQL = PASSIVE_LEVEL.
so if you not use Unicode format you can use DbgPrint or KdPrint(this is macro) at any IRQL but if you use Unicode format - only on PASSIVE_LEVEL or APC_LEVEL (about APC_LEVEL i say by self)
You can try to use the MmLockPagableCodeSection on that specific routine to prevent it being paged out, however it's probably not advisable (and you don't know what dependencies it has, if they're located in pagable sections as well). In any case, make sure you read the documentation thoroughly.
A better approach is to run at Passive/APC level in the first place before invoking the printing function - e.g., by scheduling work item (you can also force lowering the IRQL with KeLowerIrql function but it's not advisable by MSFT).
In my Informix 4GL program, I have an input field where the user can insert a URL and the feed is later being sent over to the web via a script.
How can I validate the URL at the time of input, to ensure that it's a live link? Can I make a call and see if I get back any errors?
I4GL checking the URL
There is no built-in function to do that (URLs didn't exist when I4GL was invented, amongst other things).
If you can devise a C method to do that, you can arrange to call that method through the C interface. You'll write the method in native C, and then write an I4GL-callable C interface function using the normal rules. When you build the program with I4GL c-code, you'll link the extra C functions too. If you build the program with I4GL-RDS (p-code), you'll need to build a custom runner with the extra function(s) exposed. All of this is standard technique for I4GL.
In general terms, the C interface code you'll need will look vaguely like this:
#include <fglsys.h>
// Standard interface for I4GL-callable C functions
extern int i4gl_validate_url(int nargs);
// Using obsolescent interface functions
int i4gl_validate_url(int nargs)
{
if (nargs != 1)
fgl_fatal(__FILE__, __LINE__, -1318);
char url[4096];
popstring(url, sizeof(url));
int r = validate_url(url); // Your C function
retint(r);
return 1;
}
You can and should check the manuals but that code, using the 'old style' function names, should compile correctly. The code can be called in I4GL like this:
DEFINE url CHAR(256)
DEFINE rc INTEGER
LET url = "http://www.google.com/"
LET rc = i4gl_validate_url(url)
IF rc != 0 THEN
ERROR "Invalid URL"
ELSE
MESSAGE "URL is OK"
END IF
Or along those general lines. Exactly what values you return depends on your decisions about how to return a status from validate_url(). If need so be, you can return multiple values from the interface function (e.g. error number and text of error message). Etc. This is about the simplest possible design for calling some C code to validate a URL from within an I4GL program.
Modern C interface functions
The function names in the interface library were all changed in the mid-00's, though the old names still exist as macros. The old names were:
popstring(char *buffer, int buflen)
retint(int retval)
fgl_fatal(const char *file, int line, int errnum)
You can find the revised documentation at IBM Informix 4GL v7.50.xC3: Publication library in PDF in the 4GL Reference Manual, and you need Appendix C "Using C with IBM Informix 4GL".
The new names start ibm_lib4gl_:
ibm_libi4gl_popMInt()
ibm_libi4gl_popString()
As to the error reporting function, there is one — it exists — but I don't have access to documentation for it any more. It'll be in the fglsys.h header. It takes an error number as one argument; there's the file name and a line number as the other arguments. And it will, presumably, be ibm_lib4gl_… and there'll be probably be Fatal or perhaps fatal (or maybe Err or err) in the rest of the name.
I4GL running a script that checks the URL
Wouldn't it be easier to write a shell script to get the status code? That might work if I can return the status code or any existing results back to the program into a variable? Can I do that?
Quite possibly. If you want the contents of the URL as a string, though, you'll might end up wanting to call C. It is certainly worth thinking about whether calling a shell script from within I4GL is doable. If so, it will be a lot simpler (RUN "script", IIRC, where the literal string would probably be replaced by a built-up string containing the command and the URL). I believe there are file I/O functions in I4GL now, too, so if you can get the script to write a file (trivial), you can read the data from the file without needing custom C. For a long time, you needed custom C to do that.
I just need to validate the URL before storing it into the database. I was thinking about:
#!/bin/bash
read -p "URL to check: " url
if curl --output /dev/null --silent --head --fail "$url"; then
printf '%s\n' "$url exist"
else
printf '%s\n' "$url does not exist"
fi
but I just need the output instead of /dev/null to be into a variable. I believe the only option is to dump the output into a temp file and read from there.
Instead of having I4GL run the code to validate the URL, have I4GL run a script to validate the URL. Use the exit status of the script and dump the output of curl into /dev/null.
FUNCTION check_url(url)
DEFINE url VARCHAR(255)
DEFINE command_line VARCHAR(255)
DEFINE exit_status INTEGER
LET command_line = "check_url ", url
RUN command_line RETURNING exit_status
RETURN exit_status
END FUNCTION {check_url}
Your calling code can analyze exit_status to see whether it worked. A value of 0 indicates success; non-zero indicates a problem of some sort, which can be deemed 'URL does not work'.
Make sure the check_url script (a) exits with status zero on success and non-zero on any sort of failure, and (b) doesn't write anything to standard output (or standard error) by default. The writing to standard error or output will screw up screen layouts, etc, and you do not want that. (You can obviously have options to the script that enable standard output, or you can invoke the script with options to suppress standard output and standard error, or redirect the outputs to /dev/null; however, when used by the I4GL program, it should be silent.)
Your 'script' (check_url) could be as simple as:
#!/bin/bash
exec curl --output /dev/null --silent --head --fail "${1:-http://www.example.com/"
This passes the first argument to curl, or the non-existent example.com URL if no argument is given, and replaces itself with curl, which generates a zero/non-zero exit status as required. You might add 2>/dev/null to the end of the command line to ensure that error messages are not seen. (Note that it will be hell debugging this if anything goes wrong; make sure you've got provision for debugging.)
The exec is a minor optimization; you could omit it with almost no difference in result. (I could devise a scheme that would probably spot the difference; it involves signalling the curl process, though — kill -9 9999 or similar, where the 9999 is the PID of the curl process — and isn't of practical significance.)
Given that the script is just one line of code that invokes another program, it would be possible to embed all that in the I4GL program. However, having an external shell script (or Perl script, or …) has merits of flexibility; you can edit it to log attempts, for example, without changing the I4GL code at all. One more file to distribute, but better flexibility — keep a separate script, even though it could all be embedded in the I4GL.
As Jonathan said "URLs didn't exist when I4GL was invented, amongst other things". What you will find is that the products that have grown to superceed Informix-4gl such as FourJs Genero will cater for new technologies and other things invented after I4GL.
Using FourJs Genero, the code below will do what you are after using the Informix 4gl syntax you are familiar with
IMPORT com
MAIN
-- Should succeed and display 1
DISPLAY validate_url("http://www.google.com")
DISPLAY validate_url("http://www.4js.com/online_documentation/fjs-fgl-manual-html/index.html#c_fgl_nf.html") -- link to some of the features added to I4GL by Genero
-- Should fail and display 0
DISPLAY validate_url("http://www.google.com/testing")
DISPLAY validate_url("http://www.google2.com")
END MAIN
FUNCTION validate_url(url)
DEFINE url STRING
DEFINE req com.HttpRequest
DEFINE resp com.HttpResponse
-- Returns TRUE if http request to a URL returns 200
TRY
LET req = com.HttpRequest.create(url)
CALL req.doRequest()
LET resp = req.getResponse()
IF resp.getStatusCode() = 200 THEN
RETURN TRUE
END IF
-- May want to handle other HTTP status codes
CATCH
-- May want to capture case if not connected to internet etc
END TRY
RETURN FALSE
END FUNCTION
If I execute a binary in a clearcase view, and look at /proc/self/exe for that on Linux, I see something like the following:
$ cd /proc/19220
$ ls -l exe
lrwxrwxrwx 1 peeterj pdxdb2 0 2012-11-30 13:04 exe -> /home/peeterj/views/peeterj_clang-7.vws/.s/00024/8000028250b8f1d1llvm-config
The clang llvm-config program, not unreasonably, uses this output to try to figure out the absolute fully qualified path that it is located in (I assume in case argv[0] isn't fully qualified).
Is there a way to find the location within the view that this corresponds to. For example, in this case, the llvm-config exe is actually in:
/vbs/bldsupp/linuxamd64/clang/debug/bin
(I'm wondering if it's feasible to modify clang's GetExecutablePath() function to figure this out.)
No trivial solution here (for an old version of ClearCase though):
The technote "PK27447: WITHIN A CLEARCASE DYNAMIC VIEW, THE READLINK() CALL ON LINUX RETURNS THE WRONG PATH FOR THE EXECUTABLE'S /PROC/SELF/EXE VALUE" suggests:
Local fix
Use getcwd(), get_current_dir_name(), getwd() in applications slated for a VOB/View context
Create an interposer library to intercept the readlink() call, and modify to use any of the above calls to return the proper data
The cause:
/proc/self/exe returns the improper path while getcwd succeeds.
Unfortunately, for /proc/self/exe to return the proper value [from within a VOB/View context] would require a change within the Linux kernel to allow MVFS to "override" the present setting.
IBM LTC has been working on having the Linux community adopt this change so that we can then incorporate the new features within MVFS.
Related: Bug Sun 6189256.
I wrote the following two functions, and call the second ("callAndWait") from JavaScript running inside Windows Script Host. My overall intent is to call one command line program from another. That is, I'm running the initial scripting using cscript, and then trying to run something else (Ant) from that script.
function readAllFromAny(oExec)
{
if (!oExec.StdOut.AtEndOfStream)
return oExec.StdOut.ReadLine();
if (!oExec.StdErr.AtEndOfStream)
return "STDERR: " + oExec.StdErr.ReadLine();
return -1;
}
// Execute a command line function....
function callAndWait(execStr) {
var oExec = WshShell.Exec(execStr);
while (oExec.Status == 0)
{
WScript.Sleep(100);
var output;
while ( (output = readAllFromAny(oExec)) != -1) {
WScript.StdOut.WriteLine(output);
}
}
}
Unfortunately, when I run my program, I don't get immediate feedback about what the called program is doing. Instead, the output seems to come in fits and starts, sometimes waiting until the original program has finished, and sometimes it appears to have deadlocked. What I really want to do is have the spawned process actually share the same StdOut as the calling process, but I don't see a way to do that. Just setting oExec.StdOut = WScript.StdOut doesn't work.
Is there an alternate way to spawn processes that will share the StdOut & StdErr of the launching process? I tried using "WshShell.Run(), but that gives me a "permission denied" error. That's problematic, because I don't want to have to tell my clients to change how their Windows environment is configured just to run my program.
What can I do?
You cannot read from StdErr and StdOut in the script engine in this way, as there is no non-blocking IO as Code Master Bob says. If the called process fills up the buffer (about 4KB) on StdErr while you are attempting to read from StdOut, or vice-versa, then you will deadlock/hang. You will starve while waiting for StdOut and it will block waiting for you to read from StdErr.
The practical solution is to redirect StdErr to StdOut like this:
sCommandLine = """c:\Path\To\prog.exe"" Argument1 argument2"
Dim oExec
Set oExec = WshShell.Exec("CMD /S /C "" " & sCommandLine & " 2>&1 """)
In other words, what gets passed to CreateProcess is this:
CMD /S /C " "c:\Path\To\prog.exe" Argument1 argument2 2>&1 "
This invokes CMD.EXE, which interprets the command line. /S /C invokes a special parsing rule so that the first and last quote are stripped off, and the remainder used as-is and executed by CMD.EXE. So CMD.EXE executes this:
"c:\Path\To\prog.exe" Argument1 argument2 2>&1
The incantation 2>&1 redirects prog.exe's StdErr to StdOut. CMD.EXE will propagate the exit code.
You can now succeed by reading from StdOut and ignoring StdErr.
The downside is that the StdErr and StdOut output get mixed together. As long as they are recognisable you can probably work with this.
Another technique which might help in this situation is to redirect the standard error stream of the command to accompany the standard output.
Do this by adding "%comspec% /c" to the front and "2>&1" to the end of the execStr string.
That is, change the command you run from:
zzz
to:
%comspec% /c zzz 2>&1
The "2>&1" is a redirect instruction which causes the StdErr output (file descriptor 2) to be written to the StdOut stream (file descriptor 1).
You need to include the "%comspec% /c" part because it is the command interpreter which understands about the command line redirect. See http://technet.microsoft.com/en-us/library/ee156605.aspx
Using "%comspec%" instead of "cmd" gives portability to a wider range of Windows versions.
If your command contains quoted string arguments, it may be tricky to get them right:
the specification for how cmd handles quotes after "/c" seems to be incomplete.
With this, your script needs only to read the StdOut stream, and will receive both standard output and standard error.
I used this with "net stop wuauserv", which writes to StdOut on success (if the service is running)
and StdErr on failure (if the service is already stopped).
First, your loop is broken in that it always tries to read from oExec.StdOut first. If there is no actual output then it will hang until there is. You wont see any StdErr output until StdOut.atEndOfStream becomes true (probably when the child terminates). Unfortunately, there is no concept of non-blocking I/O in the script engine. That means calling read and having it return immediately if there is no data in the buffer. Thus there is probably no way to get this loop to work as you want. Second, WShell.Run does not provide any properties or methods to access the standard I/O of the child process. It creates the child in a separate window, totally isolated from the parent except for the return code. However, if all you want is to be able to SEE the output from the child then this might be acceptable. You will also be able to interact with the child (input) but only through the new window (see SendKeys).
As for using ReadAll(), this would be even worse since it collects all the input from the stream before returning so you wouldn't see anything at all until the stream was closed. I have no idea why the example places the ReadAll in a loop which builds a string, a single if (!WScript.StdIn.AtEndOfStream) should be sufficient to avoid exceptions.
Another alternative might be to use the process creation methods in WMI. How standard I/O is handled is not clear and there doesn't appear to be any way to allocate specific streams as StdIn/Out/Err. The only hope would be that the child would inherit these from the parent but that's what you want, isn't it? (This comment based upon an idea and a little bit of research but no actual testing.)
Basically, the scripting system is not designed for complicated interprocess communication/synchronisation.
Note: Tests confirming the above were performed on Windows XP Sp2 using Script version 5.6. Reference to current (5.8) manuals suggests no change.
Yes, the Exec function seems to be broken when it comes to terminal output.
I have been using a similar function function ConsumeStd(e) {WScript.StdOut.Write(e.StdOut.ReadAll());WScript.StdErr.Write(e.StdErr.ReadAll());} that I call in a loop similar to yours. Not sure if checking for EOF and reading line by line is better or worse.
You might have hit the deadlock issue described on this Microsoft Support site.
One suggestion is to always read both from stdout and stderr.
You could change readAllFromAny to:
function readAllFromAny(oExec)
{
var output = "";
if (!oExec.StdOut.AtEndOfStream)
output = output + oExec.StdOut.ReadLine();
if (!oExec.StdErr.AtEndOfStream)
output = output + "STDERR: " + oExec.StdErr.ReadLine();
return output ? output : -1;
}